Volatile Organic Canary SAO

Did you know the smoke coming off the tip of your soldering iron is bad for you? It contains volatile organic compounds (VOCs) which can cause all kinds of nasty health problems. To keep you safe, this canary is equipped with an SGP40 VOC sensor. The display can give a numeric reading or, for a more playful way to know you're breathing in toxic chemicals, shows when the canary is "alive" or "dead". Not to worry though, since as soon as the reading returns to a safe level, the canary magically comes back to life!

Canary artwork by AlfaFilly.

Features

• SGP40 I2C VOC sensor
• SHT4x I2C temperature and humidity sensor (for accurate VOC readings)
• Two character fourteen segment display, controlled by shift registers
• RGB LED (see notes)
• ATtiny1616-S MCU
• Reprogrammable with UPDI adapter (not included)
• Multiple modes (see notes)
• Powered through SAO connector, or CR2032 battery for standalone use (included)
• Also includes a lanyard clip

Notes

• NO CLAIMS ARE MADE TO THE ACCURACY OF THIS DEVICE. IT IS FOR NOVELTY USE ONLY AND NOT TO BE RELIED UPON FOR ACCURATE MEASUREMENTS OF AIR QUALITY.
• Red and green channels for the RGB LED do not support hardware PWM. We're working on getting around this with ISRs, but no promises this will be ready in time for DEF CON. Until then, just the blue channel is utilized.
• The supported ways of measuring VOCs are a raw reading from the sensor, and the VOC index algorithm, which indicates relative changes in air quality (e.g. you move to a room with worse quality and the index rises. If you stay in the room, the index returns to nominal.) Usage of the VOC index requires a warmup period of about 10 minutes.
• v1.0 boards have been ordered. In the case issues with v0.1 (see below) have not been corrected, or other problems are introduced and cannot be resolved before DEF CON, buyers will either be able to receive a full refund or have their SAO shipped after DEF CON.
• Some minor revisions have been made between v0.1 (in photos) and v1.0 (in renders):
  • Hardware I2C has been disconnected from the SAO connector. Separate lines are now going to the connector, to prevent collisions (in the off chance another SAO is using an SGP40 sensor.)
  • Minor changes to silkscreen labeling